DESCRIPTION: Glucose is the major precursor for lactose and lipid synthesis in the lactating mammary gland, and determines the volume and energy content of milk. The long-term objective is to understand, at the molecular and cellular levels, the mechanisms and regulation of glucose transport in milk synthesis and secretion. Specific aims are: 1) to investigate the developmental regulation of glucose transport in the mammary gland; 2) to study the developmental and hormonal regulations of glucose transport in mammary epithelial cells in vitro; 3) to identify novel proteins involved in glucose transport in lactating mammary gland epithelia; and 4) to determine the role o glucose transport as a control mechanism and determinant of flux for the pathway of lactose synthesis. An improved understanding of the regulation of milk synthesis and secretion would form the basis for rational interventions t monitor and improve lactational performance, thereby prolonging the duration o breast feeding. Experiments will be performed in established cell lines, primary cells and intact and reconstituted mammary glands. Molecular cell biology techniques will be used to define developmental changes in the amount and subcellular localization of glucose transporter (GLUT1) and to identify other glucose transporters or protein affecting glucose transporter trafficking. These will be related to changes in glucose transport activity an lactose synthesis that are essential for milk production.